JPS58199188A - Heat sensitive recording paper - Google Patents

Abstract

PURPOSE:To provide heat sensitive recording paper increased in rigidity without raising cost practically and imparting bad influence to other characteristics and constituted so as to hardly generate troubles such as slip or jamming, obtained by using paper low in ash content to provide a heat sensitive recording layer. CONSTITUTION:In heat sensitive recording paper obtained by providing a heat sensitive recording layer based on a colorless or a light colored color forming substance and a color coupler developing the color of said color forming substance under heating on a paper support, the MD rigidity thereof measured by JIS P-S143 is brought to 24.0cm<2>/100 or more. By adjusting the rigidity of the recording paper to the above mentioned value, troubles such as slip, sticking or accordion like jamming are eliminated. By adjusting the rigidity to the aforementioned value by using paper manufactured by a papermaking process so as to reduce ash content to 8% or less, the recording paper free from the aforementioned troubles can be obtained without lowering recording density and raising cost practically.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to thermal recording paper, and more specifically, to a thermal recording paper comprising a thermal recording layer containing a color-forming substance and an acidic compound that develops color when heated, and a base paper. It is related to

Heat-sensitive recording sheets generally develop color through a thermal reaction between a colorless or light-colored color-forming substance such as crystal violet lactone and a phenolic compound, and generally a heat-sensitive recording composition containing the two-component coloring agent as described above is uniformly heated in water. The recording layer is coated on a support and dried to obtain heat-sensitive recording paper.The recording layer also contains color-forming properties,
For the purpose of improving pressure coloring properties, slipperiness, etc., yuzu wax particles, wax emulsions, fatty acid metal salts, fatty acids, amides, etc. are added, and clay is added to improve the whiteness and writability of the recording surface. , talc, titanium oxide, and other white pigments are often included.

Furthermore, when low-density paper is conventionally used as a support, the heat-sensitive coating liquid permeates the support, effectively reducing the amount of coloring agent remaining in the recording layer and lowering the density. I am using it. Therefore, even if the number of coating covers for the recording layer is increased, the strength of the paper as a recording paper is low, and the MD (M
achine Dirs, ction) 24.3cm3
/100. OD (Cross Dtr@cti
o'n)17. There was no thermal paper that exceeded Oc, m3/IOQ.

The recording section of a facsimile usually consists of a thermal head and a rut-feeding platen roll, and the paper is fed while recording by pressing the 1-gM recording paper between the head and the platen roll using springs, etc. . However, if recording is performed for a long time at this ms, the platen roll becomes dirty, causing problems such as paper slipping, sticking, and paper jamming in an accordion shape at the roller (hereinafter referred to as an accordion jam). ) occurs. Furthermore, if paper waste adheres to the thermal head, the above-mentioned troubles will be further exacerbated.

Numerous improvements have been proposed to solve these problems, but none of them are currently sufficiently effective and no satisfactory results have been achieved.

The present inventor discovered that the fundamental cause of these slips, stickings, and "accordion-like jams" is due to the stiffness of the recording paper, and solved the above-mentioned drawbacks by increasing the stiffness.

In the conventional technology, increasing the stiffness of thermal recording paper adversely affected other properties. In other words, is there a way to increase stiffness by lowering the density of the paper used as a support or by increasing the basis weight?If the density is lowered, f! One layer of chemicals tends to seep through the base paper, and the coating amount of the coloring layer does not increase much, resulting in a decrease in recording density, or the need to significantly increase the coating amount, which leads to increased costs. . Furthermore, it is well known that increasing the basis weight of the support also results in a significant increase in cost.

The present inventors have discovered a method of increasing the stiffness of thermal paper without increasing cost and without affecting other properties such as a decrease in density.

That is, the stiffness of thermal recording paper is MD24. Oam3/
It has been discovered that the above-mentioned drawbacks can be solved by setting the number to 100 or more.

More specifically, the stiffness of paper can be improved using the Clark method.
24. Q Om3/l O01OD 17.00!
11'7100 1: There is a limit point for paper feeding problems such as sticking, MD24.0 cm3/l
OOlOD17. If Ocm' is less than 7100, sticking or accordion-like jam will occur, but MD stiffness is 24. It has been found that when Oam'/l OO exceeds 24.0, the paper feeding performance sharply increases. More preferably, the OD stiffness is also 17. O
It has been found that paper feeding performance improves when the ratio exceeds o II''/1o o.

In addition, with conventional technology, the only way to increase the stiffness of thermal recording paper is to lower the density of the base paper to increase stiffness. This method is not used very often because the amount of coating of the coloring layer does not increase significantly, and methods for increasing stiffness have become obsolete.

That is, in the present invention, the support has an ash content of ε8%.
A heat-sensitive recording layer containing a color-forming substance and an acidic substance or a phenolic substance that causes the color-forming substance to develop color when heated is formed on the support by using a paper made with the following content (preferably 6% or less): J-K5P-814 prepared by applying
MI measured at 3) stiffness 24.0 cm3/100
The above is the thermal recording paper.

The thermal recording paper of the present invention will be explained in detail below using Examples and Comparative Example 7.

Example 1 As pulp, softwood pulp 2Qwt%, hardwood pulp f
A mixture with a ratio of lowt7≦ has a freeness of 0, s,
The paper was beaten to a weight of 45 Q ml and made into paper with a basis weight of 53.1 g/m''G using a Fourdrinier paper machine without adding ash (there was an amount of ash mixed in from the waste paper). A coating material with an ash content of 1,5 wt% as measured after papermaking was prepared as follows.

3-N-methylcyclohexylamino-6-methyl-7
-150 g of anilinofluorane (PSP-150% manufactured by Nippon Sokako Co., Ltd.), 150 g of a 5% polyvinyl alcohol (pvi)-aqueous solution, and 200 g of water were ground and dispersed in a ball mill for 48 hours to obtain a liquid A.

Also, 50g of bisphenol Al, 15% PTA aqueous solution
0g and 20g of water are similarly pulverized and dispersed to obtain liquid B, and 150g of fatty acid amide, 300g of a 5% PV membrane aqueous solution and 50g of water are similarly pulverized and dispersed to form liquid O.

A liquid 10g, B liquid 50g, 5' liquid 50g, Calcium carbonate
A paint was obtained by uniformly mixing 30 g of A and 250 g of 5% hydroxyethyl cellulose U.
'This thermal coating liquid was coated on the above-mentioned support paper so that the coating amount of the coloring agent after drying was 04 g/xn''.The thermal recording paper thus obtained was evaluated for stiffness and paper density. The results of measuring printing density, etc., are shown in Table 1 below.

Example 2 The pulp was prepared by mixing 20wt% of softwood pulp and 8Qvt% of wide milliliter pulp with a freeness of 0 and an al! 4
The paper was beaten to a volume of 5Qml, and after papermaking, the ash content was 6wt% using a Fourdrinier paper machine to reduce the basis weight to 52. The paper was made to have a concentration of ug/ml. Using this paper as a support, a paint obtained from 10 g of liquid described in Example 1, 50 g of liquid B, 50 g of liquid 10, 40 g of calcium carbonate, and 45 g of styrene-maleic acid copolymer (Maron M325, manufactured by Daido Chemical Co., Ltd.) was added to the dry color former. The coating was applied so that the coating amount was 0.45 g/m'. Regarding the thermal recording paper obtained in this way,
Table 1 shows the results of a test similar to Example 1.

Example 6 In the same manner as in Example 2, paper with a basis weight of 51.8 g/m'' was made so that the ash content after paper making was 7 wt.

Using this paper as a support, 10g5 of liquid A obtained in Example 1.
B solution 50g x' solution 50g and calcium carbonate 50g and 5
A paint was prepared from 250 g of a %Pvm aqueous solution. This paint was applied onto the above support, and the amount of color former applied after drying was 0.35.
It was applied so that it was g/ni. Table 1 shows the results of the same tests as in Example 1 performed on this thermal recording paper.

Example 4 A thermosensitive recording paper was obtained and tested in exactly the same manner as in Example 3, except that the ash content was 3 vt%. The results are shown in Table ■.

Comparative Example 1 A paper was made in the same manner as in Example 1 so that the ash content after papermaking was 1Qwt arc, and this paper was used as a support for Example 1.
The same paint as described in is used, but the amount of color former applied after drying is 0.
-4 g/m''. The obtained thermal recording paper was subjected to the same test as in Example 1, and the results are shown in Table 3.

Comparative Example 2 Using commercially available high-quality paper (basis weight 52-3 g/m", Sunflower manufactured by Tamako Paper Co., Ltd.), the same paint as described in Example 6 was applied, with the amount of coloring agent applied after drying being 0. .4g/
A heat-sensitive recording paper was obtained by coating the film in an amount of m-1.

Table 1 shows the results of the same tests as in Example 1 performed on this recording paper.

Table l Frozen paper characteristics are measured using Xerox Telecopier 485.
I performed 0m printing and investigated.

The stiffness was measured by the Clark method according to J.Eng. 5P-8143. ***Print density was printed by facsimile tester A2 using a Xerox Telecopier 485, and the density of the solid black area was measured.

Claims (1)

[Claims] A heat-sensitive recording layer comprising a colorless or light-colored color-forming substance and a color-developing substance that causes the color-forming substance to develop color when heated is provided on a support paper, and is measured according to J-Tech 5p-8143.
D stiffness is 24. Thermal recording paper with OQ"/100 or more.